Machine for making lens-grinding tools.



G. W. CONNER & J. H. PEARSON. MACHINE-FOR MAKING LENS GRINDING TOOLS.

APPLIOATION FILED MAR. 25, 1912.

1&973302. Patented May 19, 1914.

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WITNESSES: J H 1.}/)VENT0RT I A}??? I GJV ECZISOTI Charles WConner.

G. W. GONNER & J. H. PEARSON. MACHINE FOR MAKING LENS GRINDING TOOLS,

APPLICATION FILED 1\ AR.25,1912,

Patented May 19, 191%.

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ii! TNESSES:

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strait a'runfr oro CHARLES W. CONNER AND JOHN HARVEY PEAI RSON, 'OF INDIANAPOLIS, INDIANA, ASSIG-NORS TO ONE EIECE BIFOOAL LEN$ COMPANY, OF INDIANAPOLIS, INDIANA,

A. CORPORATION.

MACHINE FOR; MAKING- LENS-GRINDING TOOLS.

reasons.

To all whom it may concern Be it known that we, CHARLES lV. CON- man and .loux ll'anvnr Pearson, citizens of the lniicd States, and residents of lndianapolis, couniy of Marion, and State of Indiana, have invented a certain useful Machine for Making liens Grinding Tools; and we do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings.

The object of this invention is to provide an improved attachment for use in connection with the well known Bath grinder by which it will be possible to grind with ei- .tren1e accuracy surfaces. of compounded curvature, such as for example, a spherical surface of one radius of curvature adjacent another spherial surface of a different radius of curvature which meet in a sharply defined line and with no intermediate overlapping zone.

The invention is particularly adapted for use in bifocal optical work where it 1S'l111 perative that the lensesbe ground with extreme accuracy and with a sharp differentiation between the surfaces having a different degree of curvature.

'ihe features of the invention lie in the oscillatory mounting upon which the blank to be ground is revolubly mounted whereby a true spherical surface may be produced and also in the means by which the radius of curvature may be changed for. different portions of the blank being ground.

The nature of the invention will be understood from the accompanying drawings and the following description and claims.

In the drawings, Figure 1 is a front elevation of the grinder with our invention installed thereon. Fig- 2 is an elevation taken at ninety degrees to Fig. 1. Fig. 3 is a plan view of Fig. 2, with portions broken away and portions omitted. Fig. t is a section to a larger scale showing the swivel arm and 'wormgear for operating the same. Fig. is a plan view of a portion of the device showing the grinder, the tool being ground. the tool holder, and the gear for oscillating the same, and an altered position of the tool holder and tool being indicated by dotted lines, the parts ibeinig in Specification of Letters Patent.

Application filed March 25, 1912.

Patented May 19, 1914 Serial No. 686,099.

position for grinding the general spherical surfaceof the tool. Fig. 6 is the same show! ing the fulcrum point of the tool holding means and the gear for oscillating the same, and adjusted for grinding a portion of the surface of the tool with a less degree of curvature than the surface being ground thereon in Fig. 5.

It is to be iinderstood that in grinding one piece bifocal lenses, the convex side of the glass lens blank is cemented to a chuck which is then placed upon a grinder with the concave side of the lens bearing against a grinding blank upon the surface of which a ,curve has been ground which is the negative of the curve desired upon the blank lens. The chuck and the grinding blank are then rotated and by means of abrasive material placed upon the grinding blank, the glass lens blank in the chuck is given the desired shape. The glass is then polished, cut into two parts and finished in the usual manner. Our invention has to do with the formation of the negative curve upon the grind ng b ank. i

There is show-11in the drawings a Bath grinder of well known type having a base 10, column 11 and body 12, upon the rear sideof which a frame 13 is rigidly mounted for carrying the abrasive wheel 14:. Said wheel is driven by means of a belt 15 from an overhead driver, not shown; although this may be varied in many ways. The platen 16 of the grinder may be given the usual longitudinal and transverse movement relative to the body 12 by means of hand wheels 17 and 18, respectively. A clamping arm 19 is secured to the platen 16 and an arm 20 is oscillatably mounted between said arm and said platen. Upon an arm 21 slidably mounted on said arm 20, the grinding blank 22 is mounted and driven as hereafter described. The clamping arm 19 is secured to the left hand end of the platen 16. as shown in Fig. 1, and ex tending vertically upward therefrom with the upper end bent at substantially a right angle and upon the outer end there is an enlar ed portion or boss 23 through which a C61 '1' 24 extends whose axis is at right angles with the platen 16. The vertical cent'er 24 is adjusted by means s iniilanto the adjustment of the dead center of a lathe and the details of itare not shown, as they are well known. A knurled thumb nut is-shown in place of the hand wheel or hand crank upon the outer end of the der :1 center spindle as in the lathe. The mam portion of the arm 20 is somewhat U-shaped in cross section, the lengths of the U lying in a. horizontal position and upon the upper sidethere is a boss 26 with a central conical reces -1 27 into which the center 24; fits. Upon thel underside of the lower leg there is an extension 28 which is pivotally mounted on the platen 16 and a worm gear 29 is secured to said extension between the platen and the main body of the U. Thus the frame 20 is oscillatably mounted between the center 2st of the arm 19 and the platen 16. A shaft 30 having a worm 31 upon the right hand end, as shown in Fig. 1, and meshing with the worm gear 29, is mounted in bearings 32 upon an extension 33 from the platen l6 and upon the outer end a pulley 34 is secured'which is driven by a belt 35 from the overhead drum, not shown. There is an extension 36 secured to the lower side of the U-shaped frame 20 Which serves as a guard for the worm gear 29 and as an apron to cover a portion of the platen 16. The arm 21 is slidably mounted upon the upper side of the apron 36 having a dove tailed recess upon its underside which engages a dove tailed projection or guide 37 upon the upper side of the apron 36. Said arm may be given movement across the apron by means of a hand wheel 38 and the well known screw nut connection, not shown, between said arm and saidapron.

The arm 21, mounted as before mentioned upon the apron 36, has an upward projection 39 upon its rear end through which a dead center e0 may be advanced by turning a wheel 41 in the usual manner common to lathe and miller practice. There is a live shaft 42 mounted in an upward projection 43 upon the short side of the arm 21 or the side closest the operator, and a rib 44.- connects the front and rear projections 43 and 39 and tends to stiffen the construction.

There is a pulley 45 upon the live shaft 4.2

which is driven from any suitable overhead drive, not shown, through a belt 46. A. hand wheel e7 upon the right hand or outer end of said shaft 42 provides means whereby said shaft may be moved inward or outward as the practice demands. Preferably the end of the spindle 48 upon which the grinding blank 22 is mounted, is tapered and fits within acentral tapering socket in the end of the live shaft 42 and the other end of the blank 22 is supported upon the dead center 40, as shown in Fig. 3. The practical mode of securing and driving the spindle 48 of the grinding blank 22 is immaterial to this invention as the well known sive wheel 14 and the surface thereof can be means for mounting and securing the live center of the grlnder may be used. For this reason it has not been shown in the drawings.

The operation of our invention is as follows: The surface of the grinding blank 22 having been machined to obtain a spherical surface, the spindle 18 is centered in the live shaft 42 and with the necessary adjustments made, the various drives are started. The revolution of the worm shaft 30 will cause the arms 21 and 20 to oscillate about their pivot points and the grinding blank 22 will move past the edge of the grinding or abra 80 made to project a true spherical surface. It will be readily understood from Fig. 3, that the center of curvature of the grinding blank 22 lies in the plane of the abrasive wheel 14 and, as shown in Fig. 3, its center of curvature al.so.]ies on the axis of the spindle -18. Npw when it is desired to grind another surface upon the grinding blank 22 whose radius of curvature is greater than the radius of curvature of the surface which has just been ground, it is only necessary to move the arm 21 toward the operator by turning the hand wheel 38. This will give the arm 21 a movement at right angles to the platen 16 or the axis of the shaft of the grinder 1d and the radius of curvature of the desired surface, while increasing, still lies in the plane of the grinder le. Furthermore, the intersection of these two spherical surfaces will be in a shar line corresponding to the circumferences of circles less than that of the great circle upon the surface of the sphere being ground and there will be no intermediate zone in which the two surfaces overlap.

Figs. 5 and 6 illustrate somewhat diagrammatically the theory of operation of the device. In Fig. 5 the tool is ground to have a uniform curvature, the center of oscillation of the tool supporting mechanism being located rather close to the grinder. When the parts are'adjusted in such position, the tool is given oscillatory movement by the gear 29. In Fig. 6 a portion of the tool is being ground so as to have a curvature of much smaller degree than the curvature formed in Fig. 5, and than the curvature of the portion on each side of that portion being ground in Fig. 6. In order to get this variation in the degree of curvature of the surfaces, the fulcrum of the tool holding means must be adjusted much farther away from the grinding tool so as to increase the radius.

lVe claim as our invention I 1. A machine for making lens grinding tools including a grinding Wheel, oscillatory means for carrying the tool to be ground, and means for, varying the center of oscilla tion of said tool carrying means whereby 1 said tool may be given spherical surfaces of different degrees of curvature.

2. A machine for making lens grinding tools including a grinding wheel, oscillatory means for carrying the tool to be ground, means for rotating the tool While being ground; and means for varying the center of oscillation of said tool carrying means whereby said tool may be given spherical surfaces of different degrees of curvature.

3. A machine for making lens grinding tools including a grinding Wheel in a fixed position means for carrying the tool to be ground, an oscillatory frame in Which said tool carrying means is mounted means for locating the tool grinding means, and means for shifting the center of oscillation of said frame.

al. A machine for making lens grinding tools including a grinding Wheel in a fixed position, means for carrying the tool to be ground, a frame for supporting said tool carrying means which is pivotally mounted in substantially the same plane as the grinding Wheel, and means for shifting the center of oscillation of said frame.

5. A'machine for making lens grinding tools including a bed frame,

, a grinding Wheel mounted on said bed frame a rigid larm extending over the bed. frame, rotary tool carrying means, a frame for supporting said tool carrying means between the arm and bed frame, and movable means for oscillatably mounting said frame which may be shifted to bring the axis thereof at the center of the spherical surface desired to be given to the tool.

In witness whereof, We have hereunto afiixed our signatures in the presence of the witnesses herein named.

CHARLES XV. CON NER. J. HARVEY PEARSON. Witnesses G: H. BOINK, J. H. \VELLs. 

